1. Field of the Invention
The present invention relates to an electrochromic element for use in various types of displays and dimming devices.
2. Description of the Related Art
Electrochromic elements are conventionally equipped with a pair of spaced apart electrodes at least one of which is transparent. A pair of color-forming layers are positioned between the electrodes and an electrolyte is sandwiched between the color-forming layers. Typically, the electrodes are mounted on transparent bases such as glass or plastic.
The color-forming layers typically include an oxidative color-forming layer and a reductive color-forming layer. In one proposed construction, polyaniline is used as the oxidative color-forming layer and tungsten oxide is used as the reductive color-forming layer.
However, conventional electrochromic elements tend to have low durability. This is because sunlight deteriorates the oxidative color-forming layer made of polyaniline.
To improve the durability, some planar electrochromic dimmers are provided with filters to block ultraviolet and infrared ray. However, such filters complicate the production process as well as increase the number of parts for the electrochromic element.